In this description, the term wireless terminal refers to a device, which has means for implementing wireless communication in a wireless communication network, as well as means for executing various applications implemented by software (application programs) in the wireless terminal. The term wireless communication system, such as a mobile communication system, generally refers to any communication system, which makes a wireless data transmission connection possible between a wireless communication device and stationary parts of the system, the user of the wireless communication device moving within the operating range of the system. A typical wireless communication system is a public land mobile network PLMN. Most mobile communication systems, which are in use at the time of filing of the present application belong to the second generation of such systems, of which a well-known example is the GSM system (Global System for Mobile Telecommunications). The invention preferably relates to the next or third generation of mobile communication systems. As examples, we use the General Packet Radio Service GPRS, which is a new service for a mobile communication network presently under development, and also in use, and the third-generation Universal Mobile Telecommunications System UMTS, which is presently under standardization.
The operating environment of the GPRS system comprises one or more subnetwork service areas, which are combined to form a GPRS trunk network (FIG. 1a). The subnetworks comprise several support nodes (SN), of which the serving GPRS support nodes (SGSN) are used as examples in this description. The serving GPRS support nodes are connected to the mobile communication network (typically to a base transceiver station by means of a connection unit) in such a way that they can provide packet switching services for wireless terminals by means of base transceiver stations (cells). The mobile communication network takes care of packet switched communication between the support node and the wireless terminal. The different subnetworks, in turn, can be connected to external data networks, such as a packet switched data network (PSDN), by means of GPRS gateway support nodes (GGSN). Thus, the GPRS service enables packet data transmission between a wireless terminal and an external data network, wherein certain parts of the mobile communication network constitute an access network. Examples of applications, which utilize packet data transmission, include Internet telephone traffic, video conference, file transfer, and WWW (World Wide Web) and WAP (Wireless Application Protocol) browsing.
In third generation systems, the terms bearer service and service are used. A bearer service is a telecommunication service type, which provides the facility to transmit signals between access points. In general, the bearer service corresponds to the older term of a traffic channel, which defines, for example, the data transmission rate and the quality of service (QoS) to be used in the system when information is transmitted between a wireless terminal and another part of the system. The bearer service between the wireless terminal and the base station is, for example, a radio bearer service, and the bearer service between the radio network control unit and the core network is, for example, an lu bearer service (Interface UMTS bearer). In the UMTS system, the interface between the radio network control unit and the core network is called lu interface. In this connection, the service is provided by the mobile communication network for performing a task (tasks); for example, data services perform data transmission in the communication system, telephone services are related to telephone calls, multimedia, etc. Thus, the service requires data transmission, such as a telephone call or the transmission of text messages, between the wireless terminal and the stationary parts of the system. One important task of the operation of a third-generation mobile communication system is to control (initialize, maintain and terminate, according to the need) bearer services in such a way that each requested service can be allocated to mobile stations without wasting the available bandwidth.
The quality of service determines, for example, how packet data units (PDU) are processed in the mobile communication network during the transmission. For example, QoS levels defined for connection addresses are used for controlling the transmission order, buffering (packet strings) and rejecting packets in support nodes and gateway support nodes, particularly when two or more connections have packets to be transmitted simultaneously. The different QoS levels determine, for example, different delays for packet transmissions between the different ends of the connection, as well as different bit rates. Also, the number of rejected packet data units may vary in connections with different QoS levels.
It is possible to request for a different QoS for each connection. For example, in e-mail connections, a relatively long delay can be allowed in the transmission of messages. However, interactive applications, such as video conferences, require packet transmission at a high rate. In some applications, such as file transfers, it is important that the packet switched transmission is faultless, wherein in error situations, the packet data units are retransmitted, if necessary.
For the packet switched communication service in the UMTS system, the defining of four different traffic classes has been proposed, and for the properties of these traffic classes, the aim has been to consider the different criteria for the different connection types. On criterion defined for the first and second classes is that the transmission takes place in real time, wherein the transmission must have no significant delays. However, in such classes, the accuracy of the data transfer is not such an important property. In a corresponding manner, non-real time data transmission is sufficient for the third and fourth traffic classes, but a relatively accurate data transmission is required of them. An example of real-time first-class communication is the transmission of speech signals in a situation in which two or more persons are discussing with each other by means of wireless communication devices. An example of a situation in which real-time second-class communication might be feasible, is the transmission of a video signal for immediate viewing. Third-class non-real time packet communication can be used, for example, for the use of database services, such as the browsing of Internet home pages, in which the relative accurate data transmission at a reasonable rate is a more important factor than the real-time data transmission. In the system according to this example, for example the transfer of e-mail messages and files can be classified to the fourth category. Naturally, the number of traffic classes is not necessary four as mentioned here, but the invention can be applied in packet switched communication systems comprising any number of traffic classes. The properties of the four presented traffic classes are briefly presented in Table 1.
TABLE 1First classSecond classThird classFourth class(conversational(streaming class):(interactive class):(background class):class): real-real-time, e.g.interactive bestbackground trans-time, e.g.video informationeffort methodmission by the besttelephoneguaranteed capacityacknowledgementeffort methodconversationacknowledgementInternet browser,acknowledgementguaranteedpossibleTelnetbackground loadingcapacity nobuffering on appli-real-timeof e-mail messages,Classacknowledgementcation levelcontrol channelcalendar events, etc.Maximum<2048<2048<2048-overhead<2048-overheadbit rateTransmis-Yes/NoYes/NoYes/NoYes/Nosion orderMaximum≦1500 or 1502≦1500 or 1502≦1500 or 1502≦1500 or 1502packet size(SDU)Transmis-Yes/No/—Yes/No/—Yes/No/—Yes/No/—sion ofincorrectpackets(SDU)Residual5*10−2, 10−2,5*10−2, 10−2,4*10−3, 10−5,4*10−3, 10−5,bit error5*10−3, 10−3,5*10−3, 10−3 , 10−4,6*10−86*10−8ratio10−4, 10−610−5, 10−6Packet10−2, 7*10−3,10−1, 10−2,10−3, 10−4,10−3, 10−4,error ratio10−3, 10−4,7*10−3, 10−3,10−610−6(SDU)10−510−4, 10−5Trans-100 ms-250 ms-missionmaximum valuemaximum valuedelayGuaranteed<2048<2048bit rateTraffic1, 2, 3processingpriorityAllocation1, 2, 31, 2, 31, 2, 31, 2, 3priorityModern second and third generation wireless communication devices have much better data processing properties than older wireless communication devices. For example, they already have the facility of connecting to the Internet and using a browsing application in the wireless communication device to retrieve information from the Internet, and in the future, it will be possible to set up multimedia calls, for example, for real-time video conferences and the like. Consequently, below in this description, such wireless communication devices will be called wireless terminals. For using different applications, such a wireless terminal is provided with an execution environment for external applications, which will be called execution environment below in this description. Such execution environments are not necessarily provided solely by the manufacturer of the wireless terminal, but also some producers acting as a third party may provide such applications. To guarantee the compatibility of wireless terminals and external applications, a standard is under development for the Mobile Application Execution Environment (MExE). This invention is not limited to the standard relating to the mobile application execution environment, but it can also be applied in connection with other suitable execution environments for wireless terminals.
The user of the wireless terminal may have access to several types of services via the mobile communication network by means of the wireless terminal. For example, a vast number of service providers are connected to the Internet network. They offer a variety of services, such as database services, other information retrieval services, telephone applications, video applications, network games, etc. The user initiates a service request by starting a desired application by means of the user interface of the terminal. In the wireless terminal, the service request activates an execution environment and also the desired application. By means of the mobile communication network, the terminal sets up a connection to the Internet network or another network where the desired service is.
The requirements of different applications may be significantly different. Some applications require fast communication between the sender and the receiver. These applications include, for example, video and telephone applications. Some other applications may require as accurate data transmission as possible, but the bit rate of the data transmission connection is less important. These applications include, for example, e-mail and database applications. On the other hand, these applications can be used in several wireless communication devices with different properties. Thus, situations may occur, in which the properties of the wireless communication device do not, in all respects, correspond to the properties of the application, wherein the wireless communication device may not necessarily be capable of implementing the quality of service requested for the application. In solutions of prior art, this means that an unnecessarily high quality of service is requested for the connection, which causes, for example, that the connection takes up an unnecessarily large data transmission capacity, which may reduce the number and/or data transmission capacity of other simultaneous connections. Furthermore, these limitations on the properties of the wireless terminal may cause that the application, for which a certain quality of service is requested, does not function appropriately any longer, if the wireless terminal is not capable of meeting the QoS requirements of the application. In such a situation, the application cannot utilize the connection to be set up, wherein merely the setting up of the connection unnecessarily consumes the data transmission capacity of the mobile communication network.
Several wireless terminals are connected to networks using more than one bearer service. The network operator and/or the user may want to program the wireless terminal to use a certain bearer service to optimize a certain function, such as network loading, response times, etc. Wireless communication networks may have various bearer services to meet various QoS demands. At present, the selection of the bearer service is normally made according to the application used. The user or the network operator may classify applications according to their use of bearer services.
In present systems, the wireless terminal and the mobile communication network negotiate to select such a bearer service with which the QoS requirements can be fulfilled. For example, in the system according to the UMTS standard, the wireless terminal may freely request for a desired quality of service, wherein the UMTS mobile communication network examines if it can provide the quality of service requested by the wireless terminal. If the application to be executed in the wireless terminal contains QoS requirements, the wireless terminal transmits these QoS requirements as such to the mobile communication network, for the selection of the bearer service. However, if the application does not transmit QoS requirements to the wireless terminal, a default QoS profile stored in the network is normally used (typically in the Home Location Register, HLR), in which certain properties have been predetermined for the connection. If the properties of the wireless terminal do not, in all respects, meet the quality of service requested for the application, the performance of the application is probably not appropriate. Let us assume that the application is a video application, in which the resolution of the video image is relatively high, for example 800×640 pixels. If the user wishes to perform this video application in a wireless terminal with means for connecting it via a high-rate circuit-switched communication connection (HSCSD bearer service), and the wireless terminal is locally coupled to a portable PC with a display resolution of at least said 800×640, the application can be executed with this default resolution. If the user has only a wireless terminal comprising a display with a lower resolution, for example 640×480, the application will still try to request for a bearer service for the maximum resolution (800×640), even though a bearer service for the lower resolution (640×480) would be sufficient.